Keel Weight

[JC Uknz 1Participant @jcuknz1]

Building a 1700 cutter scaled up from the Nelson Navy static kit to be a sailing model.

Wondering if there is a sail area to keel weight ratio  ….I guess it also depends on  how far down the weight is placed and if any ballast is placed in the hull.  I’ve worked out the CoE AOK but ballast/keel is a mystery

[Bob Abell 2Participant @bobabell2]

Hello there JC

I don`t know about formulaes but I have built several Britannia type yachts….( see my albums )……………,,the hulls are 1350mm long and have a quite large sail area and yet the keel weight is only 9lb! at a keel depth of 14 inches

The models could not accomodate much more lead as the waterline footprint was quite critical!………………….They sail nicely normal windy conditions and are very graceful in light airs!

If your hull is 1700mm long……………I would use a keel depth of about 18 inches and a weight of about 12 lbs and also make the geometry of the keel blade adjustable for fore and aft and also depth

Let me know how you go on!

Regards Bob Abell

[JC Uknz 1Participant @jcuknz1]

Thankyou Bob .. hull is only about 500mm and a chunky ‘fish’ shape  with a bowsprit half as long as the hull she has a lot of sail area if perhaps a bit on the low side … I’m hoping that she doesn’t bury her nose like my footies do in hurricane winds, there is going to be quite a lot of ‘things’ on deck, cannon, crew etc 

I’m thinking of pouring [ flooding a section between bulkheads]  epoxy into the hull to make a good grip for moveable keel screwed into it through the hull .. not worked that out as yet.   She is to be a working model, minimum distance 10ft, rather than exhibition type model for close examination 

EDIT …. found your Loius Heloise which is very close to what I am building but not the Brittania .. I new to forum and still working out how it works. Interested that you put the topmast ahead of the mainmast .. which I did without paying attention to the directions I’m supposed to be working to.   I think it means the ‘topsail’ fits better to the mast … sorry I don’t know proper names for such sails.

[Bob Abell 2Participant @bobabell2]

Hello JC

So it`s only a tiddler afterall!

I mount the keel in a similar manner as One metre yachts…..the keel fits inside a loose fitting box and retained by a single screw

Just posted a photo of my Britannia yacht keel for reference………….it should appear sometime this afternoon…….with a bit of luck!

[JC Uknz 1Participant @jcuknz1]

It looks pretty big sitting on the workbench, any bigger and I would have to throw it out of the window [first floor] becuase it wouldn’t go down the stairs

[Bob Abell 2Participant @bobabell2]

OK…..I understand

[JC Uknz 1Participant @jcuknz1]

I was hoping you would tell me how you ballasted Heloise?

[Bob Abell 2Participant @bobabell2]

I`m glad you mentioned that!

I`ll post a picture in the LH forum shortly………………..it`s not a pretty sight!

Originally, the lead was carried internally, which made transportation difficult, so I used a lead keel off another model and gave it some leverage by using  thick brass strips.

[JC Uknz 1Participant @jcuknz1]

An interesting idea comes to mind prompted by your story …. design boats to suit a common keel …. would save weight when going to the pond

[JC Uknz 1Participant @jcuknz1]

weight v. sail ratio etc

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